It is generally known that heat or particularly a temperature difference can be converted directly into electrical energy by making use of the so-called “Seebeck effect” or the “thermoelectric effect”. Accordingly, devices or apparatus arrangements for directly converting heat into electrical energy have been developed to make use of such a known effect, for example in a so-called thermoelectric generator (TEG). However, the degree of efficiency of such devices is typically on the order of only about 5% in terms of the conversion of the available heat energy to the output electrical energy. Newer developments in this regard are described in the article “Small Thermoelectric Generators” by G. Jeffrey Snyder published in 2008 and available on the internet at the Internet address http://www.electrochem.org/dl/interface/fal/fal08/fal08_p54-56.pdf. Among other installations and uses, thermoelectric generators or converters are already used in isotope batteries such as Radio Isotope Thermoelectric Generators (RTG). These are advantageous in such applications because they convert heat energy directly into electrical energy without moving parts and thus without friction and without wear. Through the use of semiconductor materials, the conversion efficiency can be increased to the range from 3 to 8%, but even with the most up-to-date new materials the energy conversion efficiency still lies significantly below the Carnot Efficiency. Presently efforts are being made to use such thermoelectric generators for the recapture and conversion of waste heat, for example in motor vehicles, combined heating and power plants or cogeneration plants, waste water treatment plants and trash incineration plants.
In conventionally known applications, thermoelectric generators are often arranged in direct thermal conducting contact with the heat source. However, such an arrangement of the thermoelectric generator in direct contact with the heat source to collect or take in the heat energy can lead to problems. For example, the high operating temperatures of some heat sources, which can be up to 3400° C. for example, are too high to be directly applied to the thermoelectric generator, because typical conventionally available thermoelectric generators today can handle a maximum temperature of approximately 450° C.
U.S. Pat. No. 3,510,363 discloses a method of the abovementioned general type, in which a thermoelectric generator can also be utilized in a satellite operating in space. Namely, as disclosed in this patent, the thermoelectric generator is arranged in the interior of a closed capsule that is filled with an inert gas, and in which a suitable heat source is located. In this known use, the thermoelectric generator is particularly a Radioisotope Thermoelectric Generator (RTG), which makes use of the heat arising from the radioactive decay of a radioactive material, to carry out its function of converting the heat energy to electrical energy. In that regard, thermal conduction as well as thermal radiation form respective portions of the overall heat transport process.
Furthermore, another arrangement with a Radioisotope Thermoelectric Generator is already known from U.S. Pat. No. 3,666,566, in which the heat transmission is achieved through a heat transfer medium and thermal conduction or latent heat phase transitions. Another similar arrangement is known from the US Patent Application Publication US 2006/0,021,648. Finally, the German Patent Application Laying-Open Document DE 10 2008 031 266 A1 discloses an arrangement in which a first surface of a generator is to achieve the most immediate delay-free adaptation of the generator surface temperature to the surrounding environment temperature, while a second one of the generator surfaces is provided with means that are intended to achieve the most delayed possible adaptation of the generator surface temperature to the surrounding environmental temperature. Thereby it is intended to achieve a transient operation of such a thermoelectric generator.